The technique of stacking a plurality of semiconductor chips is known. In respect to this technique, for example, the following method is known. A lower-layer semiconductor chip is sucked and held on a suction stage and a group of bumps formed over an under surface of an upper-layer semiconductor chip sucked and held by a bonding tool are bonded to a group of bumps formed over an upper surface of the lower-layer semiconductor chip by thermocompression bonding or the like.
Japanese Laid-open Patent Publication No. 2012-089579
There may be a concavity in a surface of a semiconductor chip opposite to a surface over which a group of bumps are formed because of, for example, variation in the thickness of semiconductor substrates which occurs in a manufacturing process. When this semiconductor chip is bonded to another semiconductor chip, the surface in which the concavity is formed is sucked and held. At this time the concavity is sucked. As a result, the semiconductor chip deforms. This may lead to variation in height in the group of bumps formed over the opposite surface. If such variation in height occurs in a group of bumps of one of two semiconductor chips to be bonded together, a bonding failure may occur. For example, part of terminals or a group of terminals of the one semiconductor chip may not be bonded to corresponding terminals or a corresponding group of terminals of the other semiconductor chip.
Such a bonding failure caused by sucking and holding a surface in which a concavity is formed may occur not only in bonding groups of bumps of semiconductor chips together but also in bonding groups of terminals of various substrates, such as electronic parts and wafers, together.